Powertrain, generic · Transmission

P0994 Transmission Fluid Pressure Sensor/Switch F Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The signal of pressure sensor or switch F stays low. No manufacturer documents this code publicly. With a normally closed switch as described by Sonnax for GM's valve body modules, low means the contacts stay closed, so the module sees no pressure where pressure should be, or the signal wire is shorted to ground. GM's equivalent for switch E, P0989, flags a low signal when commanded pressure is 50 kPa or less and handles it as Special No Trip without MIL; Saab's 9-4X text gives 0 V as the low state and 12 V as high. For an analogue sensor, low would mean a voltage below its valid range. CARB requires such out-of-range checks on transmission inputs. P0995 is the high counterpart.

Likely causes

Signal wire shorted to ground
Switch stuck closed by debris or damaged film
Clutch circuit not reaching pressure (valve or seal leak)

Symptoms

  • Harsh or delayed shifts
  • Shift adaptation frozen
  • Possible limp mode

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

tfp sensor fwiring harnesstcm

Related codes

P0992P0993P0995P0996P0989

References: law.cornell.edu, sonnax.com, saabwisonline.com.